President Trump said Friday that his former national security adviser is right to seek immunity in exchange for answering questions on Russia, tweeting that Mike Flynn is caught up in a “witch hunt” of “historic proportion.”

Flynn’s attorney said Thursday that the retired general is in discussions with the House and Senate intelligence committees, indicating he wants immunity from “unfair prosecution” in exchange for answering questions on potential ties between Russia and Trump campaign associates.

Attorney Robert Kelner said Flynn “certainly has a story to tell, and he very much wants to tell it, should the circumstances permit,” but claimed he’s operating in a “highly politicized, witch hunt environment” and wants assurances.

Trump echoed that sentiment Friday.

“Mike Flynn should ask for immunity in that this is a witch hunt (excuse for big election loss), by media & Dems, of historic proportion!” he tweeted.

A congressional aide confirmed to the Associated Press that discussions with the Senate intelligence committee involved immunity.

Flynn’s ties to Russia have been scrutinized by the FBI and are under investigation by the House and Senate intelligence committees. Both committees are looking into Russia’s meddling in the 2016 presidential campaign and any ties between Trump associates and the Kremlin.

Since July, the FBI has been conducting a counterintelligence investigation into Russia’s interference in the election and possible coordination with Trump associates.

Four other Trump associates have come forward in recent weeks, saying they would talk to the committees. As of Wednesday, the Senate intelligence committee had asked to interview 20 people as part of the probe.

Trump and allied Republicans, though, say a bigger problem is the leaking of sensitive information and potential surveillance of Trump associates under the prior administration. FBI Director James Comey has denied Trump’s specific charge of wiretapping ordered by the former president, but House Intelligence Committee Chairman Devin Nunes says he’s learned some Trump team communications were incidentally collected during the transition – information he apparently found out with help from White House aides, a detail that has only fueled Democratic complaints.

In his statement, Kelner said the political climate in which Flynn is facing “claims of treason and vicious innuendo” is factoring into his negotiations with the committees.

Flynn was fired from his job as Trump’s first national security adviser after it was disclosed that he misled the vice president about a conversation he had with the Russian ambassador to the U.S. during the transition.

In the weeks after he resigned, Flynn and his business registered with the Justice Department as foreign agents for $530,000 worth of lobbying work that could have benefited the Turkish government.

The lobbying occurred while Flynn was a top Trump campaign adviser. The Turkish businessman who hired Flynn, Ekim Alptekin, has told the AP that Flynn’s firm registered under pressure from the Justice Department.